LaserCutMotors

From RepRap
Revision as of 03:14, 26 November 2011 by Glenn (talk | contribs) (+ Category:Mendel)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

General

This page and its peers should guide you through assembling a RepRap Lasercut Mendel from the TechZone kit, or from parts you have lasercut which are the same as the TechZone parts. It is a work in progress, and needs some help, feel free to edit this document to add comments of you your own, or contact us [here] and send us messages asking us for better clarification or details.

I am starting by posting the pictures I have, and over the next few days, I will fill in the instructions and detials (6 April 2011)

Thanks,
Lambert (TechZone R&D/Support/Documenter)


You can access this page and it's peers (for the other parts of the Huxley assembly from the TechZone Lasercut Mendel Page


Before installing the motors, I recommend that you hook them up to the electronics and adjust the trimpot on the electronics. The reason is that if the trimpot is up too high, the motor will get hot and warp your plastic parts. To protect your machine and all your hard work, take a few minutes to go to the first installation section of the electronics page to get the motors adjusted correctly.


Opto End Stop Preparation

X Axis Motor, Belt, and Endstop

Standard X Axis belt configuration




Install the X Axis endstop and flags
I put this endstop under an existing bolt, so that it would be close to the carriage when the carriage was in the "home" position. Alex describes which end is the home position very nicely below (better than I would have). The flag is also quite simple, it is a small piece of metal cut and bent in such a way that it goes in between the two posts of the endstop as the carriage nears the home position.



Here is my (--AlexRa 22:35, 30 January 2011 (UTC)) version of how the X belt and the optostop should be assembled)

Of the three axes, installing the X belt was the most straightforward. The only weird moment here was that the driving pulley had to be installed upside-down (with the gear towards the motor)!

Huxley X motor pulleys.jpg Huxley X idlers.jpg

Huxley Opto X.jpg

Placing the opto was not so obvious. Note that depending on what you consider the front side of the machine, you install the optos differently. I assembled mine assuming that the Y motor is in front, and the X motor is on the left. Therefore, both X and Y end stop must be on the same side with there respective motors. This does not necessary have to be so, but in any case the X opto must be on the left side and the Y one in front of you. Here is how I put it on the X axis:


Preparing the optos: the optos in TechZone kit have 3-pin connectors with 2.0mm pitch. The kit also contained some crimp connectors with 2.54 mm pitch. Besides being very difficult to install on the wire without a special crimp tool, the connectors didn't fit very well with the optical end stops. One solution is to remove the connectors from the optical end stops and solder the cable directly to them. A possible solution for the other end, and perhaps the optical end stop side too, is to solder the wire to the connector. This must be done quickly and accurately otherwise the plastic in the connector will melt (good soldering skills are advised here).


Y Axis Motor, Belt and Endstop

Alternate Y Axis Belt configuration

Alex has done a great job of figuring out an alternate belt layout, he did not like how the teeth roll over the idler bearings, so he configured it a bit differently. I like what he has done, so I am leaving it here for other people to see. There are not enough washers in the kit to do it this way, so if you decide to do the same, you will need to get more washers. (The included belt may also be too short for this configuration. --Ketil)

( here is my (--AlexRa 21:42, 30 January 2011 (UTC)) version of how the Y belt should be mounted.)

Note that the plastic Y-motor mount is similar to what's used in a full-size Mendel, and has a special extrusion for mounting 2 pulleys. However, with that path the belt meets the pulleys (or at least some of them) teeth-in. That might be acceptable for Mendel which uses larger bearings for the pulleys, but for Huxley with its 10mm bearings (and the same belt pitch) the teeth-in placement isn't a very good idea. Instead, I used 2 of the motor mounting screws to install the pulleys on them, very similar to how it's done on the X axis:

Huxley Y drive pulleys.jpg

To align the idlers with the driving gear, you need to install them about 6mm above the mounting plate. I had a few spare large (20mm) washers, so I used them here. If you don't have that many from the kit, use two M3 nuts (plus some small washers) instead. However it looks like the washers will withstand the belt tension better.

One the opposite side, another 2 idlers presumably should be installed, but I found that only one is needed. It's mounted exactly as the ones above:

Huxley Y idler pulley.jpg

Installed this way, the belt moves easily, never meets any idlers teeth-in and doesn't touch any other part of the construction (although it does come uncomfortably close to the Z belt).

Here is where I put the Y opto (in one of the holes presumably intended for the idlers). The flag is not visible on the photo. It's on the "frog" plate and has a rather trivial geometry. Once you put the opto in place, you'll see where to mount the flag.

Huxley Opto Y.jpg






The Y Axis Endstop and flag
I like to position this endstop in a location where the frog plate can be the flag. Unfortunately that position does not have a mounging hole so I recommend that you use a bit of hot glue to put it there, in this photo I show one where I drilled a new hole to mount it (I don't recommend that, it wasn't as stable as I wanted, so I ended up glueing it too)


Z Axis Motor and Belt

--AlexRa 10:07, 20 February 2011 (UTC): Here is how the assembled Z belt should look, when you use TechZone's supplied parts without modifications (photos by User:Smurf):

Z-belt with an idler

Note that the idler is very close to the nearby pulley, so one washer must either be cut (as on the photo), or just not installed:

The cut washer on the Z-idler


--AlexRa 10:07, 20 February 2011 (UTC): User:Smurf posted these photos, which show the most obvious and logical path for the Z drive. Unfortunately, this is not possible with the TechZone's supplied belt which is longer than required: it has 115 teeth, whereas for this path a belt with 110 teeth is required. At least what I got with my kit, maybe things have changed since.


(Missing images from TechZone (to be uploaded soon?)):


Z Axis Endstop


attach the Z Axis endstop and flag


Alternative Z-opto placement

--AlexRa 11:12, 20 February 2011 (UTC): Fixing the opto on the bolt and spring doesn't look very precise or reliable. I thought that a better way would be to fix the opto directly to the Z rail. If you are going to experiment with alternative hot tip designs (and that might be necessary!), you may end up with the Z-home position quite hight on the axis. In this case, even with the opto somewhat lifted by the spring, a very long flag would be required. When the opto is fixed to the Z-rail, it can be easily moved to accomodate any home position. I made my opto holder from 6mm plywood, although a printed version would look better:

Huxley Z Opto Holder.jpg

The following 1-page PDF contains the drawing of the plywood opto holder (4 parts). It is in the correct scale, so print out, cut, glue to some plywood and use your jigsaw and drill:

File:Z-Opto-Holder.pdf

Here is what you'll find in the PDF above (but this image is NOT correctly scaled!):

Huxley Z Opto Drawing.png

Printed version of the Z-opto holder

Below is the proposed RP version of the Z-opto holder. It has not been tested, as I still don't have the printer working (because of the issues with the extruder tip, see my other post for details).

Huxley Z Opto Asm.jpg

The STLs will be on Thingiverse... soonish...